1. Field of the Invention
This invention relates in general to offshore drilling systems, and in particular to a system for washing out the annulus surrounding a casing hanger when installing casing in conductor pipe with a jackup drilling rig.
2. Description of the Prior Art:
In one type of offshore drilling, jackup drilling rigs are used. Typically 30 inch diameter conductor pipe will extend from the drilling rig to a selected depth in the well. Then the operator will drill the well to a greater depth and install 20 inch diameter casing. In one technique, a casing hanger will be secured to the upper end of the string of 20 inch casing The casing hanger lands on a shoulder in the 30 inch conductor approximately at the sea floor. The operator lowers the casing hanger and string of casing with a running tool. Then the operator will pump cement down the string of casing to return up the annulus between the casing and the conductor.
After cementing, the operator will need to wash out the casing in the annulus area surrounding the casing hanger In the past, one technique used was to unscrew the running tool from the casing hanger a selected amount. This exposed wash ports leading from the interior of the running tool string to the exterior of the casing hanger. The operator would pump water down to flow out the wash ports and clean the cement from around the casing from the wash ports upward.
In U.S. Pat. No. 4,856,592, an internal sleeve locates within the running tool. The operator runs a torque member from the drilling rig down to the running tool. The torque member engages a slot on the internal sleeve. The operator rotates the torque member to rotate the sleeve. The sleeve is secured by threads to the running tool. The rotation causes the sleeve to move axially upward to expose wash ports in the running tool.